Return to Home Page
(1993 Dec. 13)
subject: superhumps of LL And, now developing
LL Andromedae
Three nights' V-band CCD photometry at Ouda revealed that this
obscure dwarf nova definitely belongs to SU UMa-type. The object is
likely to be developing its full superhumps.
The hump amplitude is still very small (~0.04 ~ 0.08 mag), but is
characterized by rather sharp minima and broad (initially doubly peaked)
maxima. The times of mimima have been successfully expressed by a
single period as indicated by the following O-C table.
Min.UT E O-C
9.379 0 -0.003
9.439 1 0.000
9.498 2 0.002
11.434 36 -0.000
11.492 37 0.001
11.550 38 0.002
12.403 53 -0.000
12.458 54 -0.002
12.518 55 0.001
12.574 56 -0.000
O-C's are calculated by the formula: Min.UT = 9.382 + 0.057006 E
The short period is really remarkable. The period is actually
shorter than the superhump period of WZ Sge itself! (0.05714 day).
This finding and rarity of the outbursts (two known outbursts occurred
14 years apart) strongly supoorts that LL And is an another member of
WZ Sge stars (extremes of SU UMa stars).
It is still unclear whether this period really settles into its
stable superhump period. Further observation is strongly encouraged
to cover the full development of the light curve and the superhumps.
Although the start of the present outburst may have been missed, the
present outburst is expected to last for two weeks or more by analogy
with WZ Sge.
The course of the present outburst is summarized below. The present
outburst was discovered by T. Vanmunster (Belgium) and confirmed by
G. Poyner (England) and P. Van Cautern (Belgium).
0001 LL Andromedae (UGSU)
0002
0003 00h 41m 51.41s
0004 +26deg 37' 20.8" (J2000.0, measured by M. Iida, VSOLJ)
0500---------------------------------------------------------------------------
0501 YYYY+
0502 MM DD.DDD MAGN MS SEQ OBSERVER NOTES SOURCE
0503---------------------------------------------------------------------------
0504
1993 11 05.577 [14.2 mv GS Moriyama, M. 33-cm refl. VSOLJ
1993 11 09.010 [15.3 mv GS Poyner, G. 40-cm refl. Mail(poy)
1993 11 12.008 [15.3 mv GS Poyner, G. 40-cm refl. Mail(poy)
1993 11 12.546 [14.2 mv GS Moriyama, M. 33-cm refl. VSOLJ
1993 11 14.914 [15.3 mv GS Poyner, G. 40-cm refl. Mail(poy)
1993 11 19.911 [14.9 mv GS Poyner, G. 40-cm refl. Mail(poy)
1993 12 06.878 [13.7 mv GS Schmeer, P. 20.3-cm SCT Mail(scp)
1993 12 07.567 [14.2 mv GS Moriyama, M. 33-cm refl. VSOLJ
1993 12 07.906 14.0 mv GS Vanmunster, T. 35-cm refl. Mail(pvc)
1993 12 07.914 [13.7 mv GS Schmeer, P. 20.3-cm SCT Mail(scp)
1993 12 07.923 13.9 mv GS Poyner, G. 40-cm refl. Mail(poy)
1993 12 07.927 13.9 mv GS Van Cautern, P. 40-cm refl. Mail(pvc)
1993 12 07.930 14.0 mv GS Poyner, G. 40-cm refl. Mail(poy)
1993 12 08.00 13.9 mv GS *Vanmunster, T. 35-cm refl. Mail(pvc)
1993 12 08.628 [14.2 mv GS Moriyama, M. 33-cm refl. VSOLJ
1993 12 09.367 14.1 V GS *Kato, T. 60-cm refl. Mail(kat)
1993 12 09.74 13.9 mv GS *Vanmunster, T. 35-cm refl. Mail(pvc)
1993 12 09.90 14.1: mv GS *Van Cautern, P. 40-cm refl. Mail(pvc)
1993 12 10.83 14.3 mv GS *Van Cautern, P. 40-cm refl. Mail(pvc)
1993 12 10.89 13.9 mv GS *Vanmunster, T. 35-cm refl. Mail(pvc)
1993 12 11.476 14.2 V GS *Kato, T. 60-cm refl. Mail(kat)
Regards,
Taichi Kato (Kyoto University)
Return to the Powerful Daisaku Nogami
vsnet-adm@kusastro.kyoto-u.ac.jp
